The present invention relates generally to telephone systems and, more particularly, to the detection of mis-routing of calls.
1. Introductory Remarks
In the telephone system post-divestiture environment, complex regulatory tariffs have been mandated and/or inter-carrier contracts have been negotiated between carriers which (a) regulate the way in which traffic is to be routed between them and (b) specify the rates at which various types of traffic are to be charged. It is often of financial advantage to mis-route calls in violation of these existing regulatory tariffs and/or established inter-carrier contracts. The common name for this manipulation is xe2x80x9carbitragexe2x80x9d. The intent of those perpetrating this mis-routing is to take advantage of lower rates associated with the delivery of telephone traffic via other than the proper routes. Confirming the presence of arbitrage and proper billing is often difficult due to the fact that call routing information is often missing or incomplete.
2. Definitions
In general, the following definitions are common in the telephone industry, but are included herein for completeness and clarity of explanation. They define the meanings of these terms as used in the Present Patent Document.
A compensation mechanism governed by tariffs and/or contracts for message traffic carried by interexchange carriers (IXC) and exchanged between the IXC""s and local exchange carriers (LEC""s), independent local exchange carrier (ILEC""s), and competitive local exchange carrier (CLEC""s). This type of traffic is generally carried over a type of telephone trunk called a Feature Group D trunk or FG-D trunk, and typically carries the highest per-minute charge. Under access traffic, IXC""s pay the other carriers for each Minute of Use (MOU) of traffic destined to the IXC or originating from the IXC.
The time at which the telephone being called began alerting the user (e.g. ringing).
The Address Complete Message (ACM) is used to acknowledge receipt of an initial address message (IAM) and to indicate that the called party is being alerted (e.g. via ringing).
The time the operator of the telephone being called answered the telephone.
The Answer Message (ANM) is used to indicate that the user called has answered, end to end connection is established, and a conversation takes place.
As used herein and as commonly used in the telephone industry, it is the mis-routing of inter-carrier telephone calls in such a way as to violate existing regulatory tariffs and/or established inter-carrier contracts. The purpose of such mis-routing is typically to take advantage of lower rates associated with the delivery of telephone traffic via routes other than those established and required by such tariffs and contracts and as such may be fraudulent. Arbitrage typically occurs via the following techniques: (1) interexchange carrier (IXC) access traffic delivered via competitive local exchange carriers (CLEC""s) and (2) transit traffic delivered via non-transit trunks
An indicator as to whether Signaling System 7 (SS7) and non-SS7 inter-working was encountered ahead of this point in the call.
A collection of messages comprising parameters and time-stamps associated with each call which provide detail regarding the call origin, destination, and other details.
The telephone number dialed by the calling user.
The telephone number of the user making the call.
Parameters contained within the Signaling System 7 (SS7) Initial Address Message (IAM) message which can be used to identify the requested interexchange carrier (IXC).
The number identifying the interexchange carrier (IXC) selected by the Local Exchange Carrier.
The telephone number to which the call is charged. Typically it is the telephone number of the calling telephone.
A local exchange carrier (LEC) but specifically referring to one that competes with the incumbent local exchange carrier (LEC).
The Signaling System 7 (SS7) node [e.g. switching office or Signaling Transfer Point (STP)] that the message is being sent to.
A switching office normally referred to as an end office or xe2x80x9ceoxe2x80x9d to which telephones (from homes or businesses) are connected via wires called xe2x80x9cloopsxe2x80x9d.
A type of telephone trunk. See Access Traffic.
An indicator as to whether Signaling System 7 (SS7) and non-SS7 inter-working was encountered prior to the point in the call where the parameter is observed.
The time the trunk was seized for transmission of an SS7 message.
Generally refers to a local exchange carrier (LEC) which co-existed with a local exchange carrier owned by the Regional Bell Operating Companies.
The Initial Address Message (IAM) is used to indicate the desire to set up a call. A trunk is seized and xe2x80x9creservedxe2x80x9d for use in the call.
Any carrier that interconnects with the local exchange carrier (LEC).
An interexchange carrier (IXC) transports calls from one local exchange carrier (LEC) to another, or possibly the same LEC, throughout the IXC""s serving area. The IXC""s serving area would typically span more than one local access transport area (LATA), and the IXC receives messages from and delivers messages to local exchange carriers (LEC""s, CLEC""s, and ILEC""s) and other interchange carriers (IXC""s). Calls that span local area transport areas (LATA""sxe2x80x94geographical regions defined at divestiture) typically must use an IXC.
A trunk that comes from an interexchange carrier to a local exchange carrier.
A parameter contained in SS7 messages which, if available, indicates the geographic origin of a call.
A system that can be used to collect Call Detail Records (CDR""s) by monitoring SS7 links.
The geographic area within which a local exchange carrier (LEC) provides service is typically divided into various areas referred to as local access transport areas (LATA""s).
A local exchange carrier (LEC) is a telephone service provider that provides telephone service to its customers in a specific geographical serving area. A local exchange carrier (LEC) would typically be a local telephone company.
A document defining the specific local access transport area (LATA) within which a given telephone number is located.
A number obtained from the database at the service control point (SCP). The SCP converts the called number into the LRN which is the number used by the network to get the call to its final destination.
Telephones are connected (from homes or businesses) via wires called xe2x80x9cloopsxe2x80x9d to a switching office normally referred to as an end office or xe2x80x9ceoxe2x80x9d.
Traffic exchanged between interexchange carriers (IXC""s) and independent local exchange carriers (ILEC""s) destined for local exchange carrier (LEC) customers (in cases where the IXC does not directly interconnect with the LEC) is governed by tariffs and/or contracts, using a compensation mechanism referred to as meet-point billing. Under meet-point billing, IXC""s pay the ILEC a fee, part of which is subsequently paid by the ILEC to the LEC for each Minute of Use (MOU) of traffic between the IXC and the LEC.
For billing purposes a measure of the time which a given carrier""s resources are consumed providing a given service.
More commonly known as the area code of the telephone number.
The numbering plan address (i.e., the area code) plus the next three digits of the telephone number.
The Signaling System 7 (SS7) node [e.g. switching office or Signaling Transfer Point (STP)] that is sending the message.
Under reciprocal compensation, carriers pay each other a usage fee for each Minute of Use (MOU) of traffic delivered from their network to the other carrier""s network. This message traffic is typically traffic exchanged between various local exchange carriers (LEC""s) and their competitive local exchange carriers (CLEC""s) and independent local exchange carriers (LEC""s). This type of traffic is generally carried over a type of telephone trunk called a local trunk.
The Release Complete Message (RLC) is sent when the second of the two connected parties hangs up. At that point the trunk is released.
The Release Message (REL) indicates that the first of the two connected parties has hung up.
The time the operator of the first telephone to hang up did so.
A device used to consolidate partial Call Detail Records (CDR""s) into complete CDR""s.
The time the operator of the second telephone to hang up did so.
A network database used to translate called numbers into local routing number which translates the called number in the location routing number (LRN).
At the heart of the SS7 network are packet switches known as Signaling Transfer Points (STP""s). STP""s are deployed in pairs in the North American SS7 network to provide communication path redundancy. Different carriers own a portion of the SS7 network and interconnect their end offices (eo""s) and tandem""s to the overall SS7 network so as to enable end-to-end communication between carriers.
The communication links over which Signaling System 7 (SS7) traffic is carried.
The Signaling System 7 (SS7) messages are transported over a secure data network referred to as the xe2x80x9cSS7 networkxe2x80x9d. The SS7 network comprises various SS7 Links along with Signaling Transfer Points (STP""s).
To perform the task of call setup and tear down when multiple end offices (eo""s) are involved, switching offices communicate with each other using a signaling protocol referred to as Signaling System 7 (SS7), carried over SS7 links. SS7 messages are used in specific sequences to perform various tasks required to establish telephone connections. Telephone calls between two customers connected to the same eo will be handled by the application logic contained in the eo, and will not require the use of the SS7 protocol.
In certain cases, for example two towns that are somewhat far apart, a type of switching center called a xe2x80x9ctandemxe2x80x9d is involved in establishing connectivity between two customers.
Trunk Circuit Identification Code. Between any two telephone switches there may a trunk group which comprises several trunks. These trunks are identified via the TCIC.
Parameters contained within the Signaling System 7 (SS7) Initial Address Message (IAM) message which can be used to identify the requested interexchange carrier (IXC).
Traffic that goes thru a LEC network but does not originate or terminate in that LEC and uses trunks other than those specifically designated for such traffic.
When telephones are served from different eo""s (e.g. in different towns), they are interconnected via wires called xe2x80x9ctrunksxe2x80x9d between the eo""s.
A communication network serving a large geographical area of interest.
4. Discussion
Previous methods for the determination of telephone traffic routing have been based upon a single call sample, e.g. a call record obtained at the point where the call originates or at the point where the call terminates. The information available within a single call record has limitations due to the fact that critical routing information may be (a) missing or (b) incorrect. These techniques have proven to be ineffective at determining the presence of arbitrage. Since in typical arbitrage situations, the local exchange carrier is under billing the interexchange carriers, there is a great financial incentive for the local exchange carrier to detect and stop arbitrage, and since previous methods are both unreliable and labor intensive, there is a great need for improved means for detecting arbitrage.
The present patent document discloses novel methods for the correlation of calling records and for the detection of mis-routing of traffic in a telephone or other communication system. Previous methods for detection of mis-routing have been based upon a single call sample, e.g. a call-record obtained at the point where the call originates or at the point where the call terminates. The information available within a single call record has limitations due to the fact that critical routing information may be (a) missing or (b) incorrect, and these techniques have proven to be ineffective at determining the presence of arbitrage. Correlation of call detail records obtained from various communication segments provides the ability to mutually enrich the records so as to increase billing accuracy as well as to enhance the detection of call mis-routing.
Techniques disclosed in the present patent document can be used to identify inter-carrier telephone calls that are being mis-routed in such a way as to violate existing regulatory tariffs and/or established inter-carrier contracts The common name for this manipulation is xe2x80x9carbitragexe2x80x9d, and the intent of the perpetrators is to take advantage of lower rates associated with the delivery of telephone traffic via routes other than those legislated or contracted. Through the process of correlation in representative embodiments, various call xe2x80x9clegsxe2x80x9d associated with the same call can be identified, and a more accurate xe2x80x9ccompoundxe2x80x9d call record can be made that incorporates call routing information obtained from the individual call legs.
In a representative embodiment, a basic approach to arbitrage detection is to correlate inbound calls from a competitive local exchange carrier (CLEC) to a local exchange carrier (LEC) with the corresponding outbound calls at their point of origin. Correlation can be obtained via a variety of data obtained from call detail records in the SS7 network.
The correlation feature of the link monitoring system (LMS) is the primary tool used to implement arbitrage detection. Call detail records (CDR""s) are collected throughout the LEC footprint and xe2x80x9ccorrelatedxe2x80x9d at the time of their load into the call detail record database. The correlation method comprises identifying call segments via call detail records wherein (1) the called station numbers are identical and (2) the time of call initiation and the time the first party hangs up match within a configurable, but very small, time difference. The correlation method typically applies different time thresholds depending upon whether the call segments being correlated are deemed to be adjacent (e g. on either side of a tandem), or non-adjacent (e.g. more than two tandems away from each other).
In order to eliminate false correlations (i.e., to disassociate call segments that really are not related to the same call), attempts are made to increase the correlation confidence by correlating other pieces of call setup information from the various call segments. Specifically, further efforts can be made to (1) confirm that the time the connection for the call was completed matches within a configurable, but very small, time difference, (2) insuring that the calling number information parameters match, (3) insuring that charge number information parameters match, and/or (4) insuring that jurisdiction information parameters match.
Additional constraints can be applied to select calls that fit the criteria of arbitrage, and to exclude calls that may be correlated for other legitimate reasons or duplicate call segments that may have been collected due to over-provisioning of the link monitoring systems.
A measure of the probability of arbitrage is based upon the combinations of characteristics that are present. Once suspected, SS7 call detail records are randomly chosen and compared with billing records to confirm arbitrage. Once arbitrage is confirmed, the characteristics of known arbitrators can be further refined. Traffic profiles of carriers can be created that contain historical traffic information. Arbitrage may be suspected whenever the traffic profiles of two or more carriers change in ways inversely proportional to each other, suggesting the redirection of traffic from one carrier to another. Once suspected, SS7 call detail records can be analyzed in further detail to confirm the arbitrage